And that AARP paper is specifically talking about means testing non-Social Security income once benefits would have begun. Still not the same as a cumulative asset test. The income test already happens somewhat by taxing SS benefits above a certain amount.
The paper also talks about only affecting about 9% of all retirees with the means test proposed. It proposes $110,000 in non-SS income as the threshold for a couple at which benefifs would start dropping. People that have figured out how to live comfortably on $40,000-60,000 wouldn't be affected. I don't see anything to worry about, new means testing proposal or not.